In signal processing, correlation is a measure of similarity of two waveforms. For example, a received signal may be compared as it is received with a desired waveform. The response of the correlator is a function of the similarity of the waveforms and is maximized when there is an exact match between the received waveform and the desired waveform. A correlator may be efficiently implemented as a finite impulse response (FIR) filter.
Real-time correlators can be implemented via analog transversal filters such as analog tapped delay lines or surface acoustic wave (SAW) filters; however, these implementations suffer from inflexibility, because the analog tap delays or SAW filter weights cannot be adjusted. SAW devices also suffer bandwidth limitations.
Correlators can be implemented with digital logic; however, if the signal to be processed is an analog waveform, then a digital correlator requires an analog to digital converter (ADC) to convert the analog waveform to digital. A digital correlator requires more power and area, and operates at a lower speed than an analog correlator. However, when very high precision is required, a digital correlator may be superior to an analog correlator.
What is needed is a filter and correlator with adjustable tap delays and adjustable tap coefficients that is faster, that has requires less area and lower power than a full digital implementation, and that has a higher bandwidth than SAW filters, while offering the benefit of feature scaling as integrated circuit technology improves. The embodiments of the present disclosure answer these and other needs.